Merge branch 'bc/object-id-part17'

Preparation for SHA-256 upgrade continues.

* bc/object-id-part17: (26 commits)
  midx: switch to using the_hash_algo
  builtin/show-index: replace sha1_to_hex
  rerere: replace sha1_to_hex
  builtin/receive-pack: replace sha1_to_hex
  builtin/index-pack: replace sha1_to_hex
  packfile: replace sha1_to_hex
  wt-status: convert struct wt_status to object_id
  cache: remove null_sha1
  builtin/worktree: switch null_sha1 to null_oid
  builtin/repack: write object IDs of the proper length
  pack-write: use hash_to_hex when writing checksums
  sequencer: convert to use the_hash_algo
  bisect: switch to using the_hash_algo
  sha1-lookup: switch hard-coded constants to the_hash_algo
  config: use the_hash_algo in abbrev comparison
  combine-diff: replace GIT_SHA1_HEXSZ with the_hash_algo
  bundle: switch to use the_hash_algo
  connected: switch GIT_SHA1_HEXSZ to the_hash_algo
  show-index: switch hard-coded constants to the_hash_algo
  blame: remove needless comparison with GIT_SHA1_HEXSZ
  ...

31 files changed, 121 insertions, 125 deletions

diff --git a/bisect.c b/bisect.c
index e87ac29a51..e81c91d02c 100644
--- a/bisect.c
+++ b/bisect.c
@@ -707,7 +707,7 @@ static int bisect_checkout(const struct object_id *bisect_rev, int no_checkout)
 {
 	char bisect_rev_hex[GIT_MAX_HEXSZ + 1];
 
-	memcpy(bisect_rev_hex, oid_to_hex(bisect_rev), GIT_SHA1_HEXSZ + 1);
+	memcpy(bisect_rev_hex, oid_to_hex(bisect_rev), the_hash_algo->hexsz + 1);
 	update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
 
 	argv_checkout[2] = bisect_rev_hex;
diff --git a/blame.c b/blame.c
index 36a2e7ef11..6596d8de88 100644
--- a/blame.c
+++ b/blame.c
@@ -144,7 +144,7 @@ static void append_merge_parents(struct repository *r,
 
 	while (!strbuf_getwholeline_fd(&line, merge_head, '\n')) {
 		struct object_id oid;
-		if (line.len < GIT_SHA1_HEXSZ || get_oid_hex(line.buf, &oid))
+		if (get_oid_hex(line.buf, &oid))
 			die("unknown line in '%s': %s",
 			    git_path_merge_head(r), line.buf);
 		tail = append_parent(r, tail, &oid);
diff --git a/builtin/blame.c b/builtin/blame.c
index b6534d4dea..5a0c0c2312 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -460,7 +460,7 @@ static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int
 
 	for (cnt = 0; cnt < ent->num_lines; cnt++) {
 		char ch;
-		int length = (opt & OUTPUT_LONG_OBJECT_NAME) ? GIT_SHA1_HEXSZ : abbrev;
+		int length = (opt & OUTPUT_LONG_OBJECT_NAME) ? the_hash_algo->hexsz : abbrev;
 
 		if (opt & OUTPUT_COLOR_LINE) {
 			if (cnt > 0) {
@@ -885,6 +885,7 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 	struct range_set ranges;
 	unsigned int range_i;
 	long anchor;
+	const int hexsz = the_hash_algo->hexsz;
 
 	setup_default_color_by_age();
 	git_config(git_blame_config, &output_option);
@@ -931,11 +932,11 @@ parse_done:
 	} else if (show_progress < 0)
 		show_progress = isatty(2);
 
-	if (0 < abbrev && abbrev < GIT_SHA1_HEXSZ)
+	if (0 < abbrev && abbrev < hexsz)
 		/* one more abbrev length is needed for the boundary commit */
 		abbrev++;
 	else if (!abbrev)
-		abbrev = GIT_SHA1_HEXSZ;
+		abbrev = hexsz;
 
 	if (revs_file && read_ancestry(revs_file))
 		die_errno("reading graft file '%s' failed", revs_file);
diff --git a/builtin/clone.c b/builtin/clone.c
index 2048b6760a..096be383cd 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -785,7 +785,7 @@ static int checkout(int submodule_progress)
 	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 		die(_("unable to write new index file"));
 
-	err |= run_hook_le(NULL, "post-checkout", sha1_to_hex(null_sha1),
+	err |= run_hook_le(NULL, "post-checkout", oid_to_hex(&null_oid),
 			   oid_to_hex(&oid), "1", NULL);
 
 	if (!err && (option_recurse_submodules.nr > 0)) {
diff --git a/builtin/commit.c b/builtin/commit.c
index ae7aaf6dc6..e588bc6ad3 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -510,7 +510,7 @@ static int run_status(FILE *fp, const char *index_file, const char *prefix, int
 	s->nowarn = nowarn;
 	s->is_initial = get_oid(s->reference, &oid) ? 1 : 0;
 	if (!s->is_initial)
-		hashcpy(s->sha1_commit, oid.hash);
+		oidcpy(&s->oid_commit, &oid);
 	s->status_format = status_format;
 	s->ignore_submodule_arg = ignore_submodule_arg;
 
@@ -1406,7 +1406,7 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 
 	s.is_initial = get_oid(s.reference, &oid) ? 1 : 0;
 	if (!s.is_initial)
-		hashcpy(s.sha1_commit, oid.hash);
+		oidcpy(&s.oid_commit, &oid);
 
 	s.ignore_submodule_arg = ignore_submodule_arg;
 	s.status_format = status_format;
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index a23454da6e..60a5591039 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1490,11 +1490,11 @@ static void final(const char *final_pack_name, const char *curr_pack_name,
 	}
 
 	if (!from_stdin) {
-		printf("%s\n", sha1_to_hex(hash));
+		printf("%s\n", hash_to_hex(hash));
 	} else {
 		struct strbuf buf = STRBUF_INIT;
 
-		strbuf_addf(&buf, "%s\t%s\n", report, sha1_to_hex(hash));
+		strbuf_addf(&buf, "%s\t%s\n", report, hash_to_hex(hash));
 		write_or_die(1, buf.buf, buf.len);
 		strbuf_release(&buf);
 
diff --git a/builtin/patch-id.c b/builtin/patch-id.c
index bd28b80b2d..3059e525b8 100644
--- a/builtin/patch-id.c
+++ b/builtin/patch-id.c
@@ -1,15 +1,16 @@
+#include "cache.h"
 #include "builtin.h"
 #include "config.h"
 #include "diff.h"
 
 static void flush_current_id(int patchlen, struct object_id *id, struct object_id *result)
 {
-	char name[50];
+	char name[GIT_MAX_HEXSZ + 1];
 
 	if (!patchlen)
 		return;
 
-	memcpy(name, oid_to_hex(id), GIT_SHA1_HEXSZ + 1);
+	memcpy(name, oid_to_hex(id), the_hash_algo->hexsz + 1);
 	printf("%s %s\n", oid_to_hex(result), name);
 }
 
@@ -60,9 +61,9 @@ static int get_one_patchid(struct object_id *next_oid, struct object_id *result,
 {
 	int patchlen = 0, found_next = 0;
 	int before = -1, after = -1;
-	git_SHA_CTX ctx;
+	git_hash_ctx ctx;
 
-	git_SHA1_Init(&ctx);
+	the_hash_algo->init_fn(&ctx);
 	oidclr(result);
 
 	while (strbuf_getwholeline(line_buf, stdin, '\n') != EOF) {
@@ -122,7 +123,7 @@ static int get_one_patchid(struct object_id *next_oid, struct object_id *result,
 		/* Compute the sha without whitespace */
 		len = remove_space(line);
 		patchlen += len;
-		git_SHA1_Update(&ctx, line, len);
+		the_hash_algo->update_fn(&ctx, line, len);
 	}
 
 	if (!found_next)
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index dcf385511f..411e0b4d99 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -417,24 +417,22 @@ static int copy_to_sideband(int in, int out, void *arg)
 	return 0;
 }
 
-#define HMAC_BLOCK_SIZE 64
-
-static void hmac_sha1(unsigned char *out,
+static void hmac(unsigned char *out,
 		      const char *key_in, size_t key_len,
 		      const char *text, size_t text_len)
 {
-	unsigned char key[HMAC_BLOCK_SIZE];
-	unsigned char k_ipad[HMAC_BLOCK_SIZE];
-	unsigned char k_opad[HMAC_BLOCK_SIZE];
+	unsigned char key[GIT_MAX_BLKSZ];
+	unsigned char k_ipad[GIT_MAX_BLKSZ];
+	unsigned char k_opad[GIT_MAX_BLKSZ];
 	int i;
-	git_SHA_CTX ctx;
+	git_hash_ctx ctx;
 
 	/* RFC 2104 2. (1) */
-	memset(key, '\0', HMAC_BLOCK_SIZE);
-	if (HMAC_BLOCK_SIZE < key_len) {
-		git_SHA1_Init(&ctx);
-		git_SHA1_Update(&ctx, key_in, key_len);
-		git_SHA1_Final(key, &ctx);
+	memset(key, '\0', GIT_MAX_BLKSZ);
+	if (the_hash_algo->blksz < key_len) {
+		the_hash_algo->init_fn(&ctx);
+		the_hash_algo->update_fn(&ctx, key_in, key_len);
+		the_hash_algo->final_fn(key, &ctx);
 	} else {
 		memcpy(key, key_in, key_len);
 	}
@@ -446,29 +444,29 @@ static void hmac_sha1(unsigned char *out,
 	}
 
 	/* RFC 2104 2. (3) & (4) */
-	git_SHA1_Init(&ctx);
-	git_SHA1_Update(&ctx, k_ipad, sizeof(k_ipad));
-	git_SHA1_Update(&ctx, text, text_len);
-	git_SHA1_Final(out, &ctx);
+	the_hash_algo->init_fn(&ctx);
+	the_hash_algo->update_fn(&ctx, k_ipad, sizeof(k_ipad));
+	the_hash_algo->update_fn(&ctx, text, text_len);
+	the_hash_algo->final_fn(out, &ctx);
 
 	/* RFC 2104 2. (6) & (7) */
-	git_SHA1_Init(&ctx);
-	git_SHA1_Update(&ctx, k_opad, sizeof(k_opad));
-	git_SHA1_Update(&ctx, out, GIT_SHA1_RAWSZ);
-	git_SHA1_Final(out, &ctx);
+	the_hash_algo->init_fn(&ctx);
+	the_hash_algo->update_fn(&ctx, k_opad, sizeof(k_opad));
+	the_hash_algo->update_fn(&ctx, out, the_hash_algo->rawsz);
+	the_hash_algo->final_fn(out, &ctx);
 }
 
 static char *prepare_push_cert_nonce(const char *path, timestamp_t stamp)
 {
 	struct strbuf buf = STRBUF_INIT;
-	unsigned char sha1[GIT_SHA1_RAWSZ];
+	unsigned char hash[GIT_MAX_RAWSZ];
 
 	strbuf_addf(&buf, "%s:%"PRItime, path, stamp);
-	hmac_sha1(sha1, buf.buf, buf.len, cert_nonce_seed, strlen(cert_nonce_seed));
+	hmac(hash, buf.buf, buf.len, cert_nonce_seed, strlen(cert_nonce_seed));
 	strbuf_release(&buf);
 
 	/* RFC 2104 5. HMAC-SHA1-80 */
-	strbuf_addf(&buf, "%"PRItime"-%.*s", stamp, GIT_SHA1_HEXSZ, sha1_to_hex(sha1));
+	strbuf_addf(&buf, "%"PRItime"-%.*s", stamp, (int)the_hash_algo->hexsz, hash_to_hex(hash));
 	return strbuf_detach(&buf, NULL);
 }
 
@@ -970,7 +968,7 @@ static const char *push_to_deploy(unsigned char *sha1,
 	if (run_command(&child))
 		return "Working directory has staged changes";
 
-	read_tree[3] = sha1_to_hex(sha1);
+	read_tree[3] = hash_to_hex(sha1);
 	child_process_init(&child);
 	child.argv = read_tree;
 	child.env = env->argv;
@@ -987,13 +985,13 @@ static const char *push_to_deploy(unsigned char *sha1,
 
 static const char *push_to_checkout_hook = "push-to-checkout";
 
-static const char *push_to_checkout(unsigned char *sha1,
+static const char *push_to_checkout(unsigned char *hash,
 				    struct argv_array *env,
 				    const char *work_tree)
 {
 	argv_array_pushf(env, "GIT_WORK_TREE=%s", absolute_path(work_tree));
 	if (run_hook_le(env->argv, push_to_checkout_hook,
-			sha1_to_hex(sha1), NULL))
+			hash_to_hex(hash), NULL))
 		return "push-to-checkout hook declined";
 	else
 		return NULL;
diff --git a/builtin/repack.c b/builtin/repack.c
index 3b3dd14372..094c2f8ea4 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -191,7 +191,7 @@ static int write_oid(const struct object_id *oid, struct packed_git *pack,
 			die(_("could not start pack-objects to repack promisor objects"));
 	}
 
-	xwrite(cmd->in, oid_to_hex(oid), GIT_SHA1_HEXSZ);
+	xwrite(cmd->in, oid_to_hex(oid), the_hash_algo->hexsz);
 	xwrite(cmd->in, "\n", 1);
 	return 0;
 }
diff --git a/builtin/replace.c b/builtin/replace.c
index 2a4afb3b93..bd92dc63b9 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -272,7 +272,7 @@ static int import_object(struct object_id *oid, enum object_type type,
 			return error(_("unable to spawn mktree"));
 		}
 
-		if (strbuf_read(&result, cmd.out, 41) < 0) {
+		if (strbuf_read(&result, cmd.out, the_hash_algo->hexsz + 1) < 0) {
 			error_errno(_("unable to read from mktree"));
 			close(fd);
 			close(cmd.out);
@@ -358,14 +358,15 @@ static int replace_parents(struct strbuf *buf, int argc, const char **argv)
 	struct strbuf new_parents = STRBUF_INIT;
 	const char *parent_start, *parent_end;
 	int i;
+	const unsigned hexsz = the_hash_algo->hexsz;
 
 	/* find existing parents */
 	parent_start = buf->buf;
-	parent_start += GIT_SHA1_HEXSZ + 6; /* "tree " + "hex sha1" + "\n" */
+	parent_start += hexsz + 6; /* "tree " + "hex sha1" + "\n" */
 	parent_end = parent_start;
 
 	while (starts_with(parent_end, "parent "))
-		parent_end += 48; /* "parent " + "hex sha1" + "\n" */
+		parent_end += hexsz + 8; /* "parent " + "hex sha1" + "\n" */
 
 	/* prepare new parents */
 	for (i = 0; i < argc; i++) {
diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index f8bbe6d47e..308c67e4fc 100644
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -593,6 +593,7 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 	const char *name = NULL;
 	struct object_context unused;
 	struct strbuf buf = STRBUF_INIT;
+	const int hexsz = the_hash_algo->hexsz;
 
 	if (argc > 1 && !strcmp("--parseopt", argv[1]))
 		return cmd_parseopt(argc - 1, argv + 1, prefix);
@@ -730,8 +731,8 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 				abbrev = strtoul(arg, NULL, 10);
 				if (abbrev < MINIMUM_ABBREV)
 					abbrev = MINIMUM_ABBREV;
-				else if (40 <= abbrev)
-					abbrev = 40;
+				else if (hexsz <= abbrev)
+					abbrev = hexsz;
 				continue;
 			}
 			if (!strcmp(arg, "--sq")) {
diff --git a/builtin/show-index.c b/builtin/show-index.c
index a6e678809e..0826f6a5a2 100644
--- a/builtin/show-index.c
+++ b/builtin/show-index.c
@@ -11,6 +11,7 @@ int cmd_show_index(int argc, const char **argv, const char *prefix)
 	unsigned nr;
 	unsigned int version;
 	static unsigned int top_index[256];
+	const unsigned hashsz = the_hash_algo->rawsz;
 
 	if (argc != 1)
 		usage(show_index_usage);
@@ -36,23 +37,23 @@ int cmd_show_index(int argc, const char **argv, const char *prefix)
 	}
 	if (version == 1) {
 		for (i = 0; i < nr; i++) {
-			unsigned int offset, entry[6];
+			unsigned int offset, entry[(GIT_MAX_RAWSZ + 4) / sizeof(unsigned int)];
 
-			if (fread(entry, 4 + 20, 1, stdin) != 1)
+			if (fread(entry, 4 + hashsz, 1, stdin) != 1)
 				die("unable to read entry %u/%u", i, nr);
 			offset = ntohl(entry[0]);
-			printf("%u %s\n", offset, sha1_to_hex((void *)(entry+1)));
+			printf("%u %s\n", offset, hash_to_hex((void *)(entry+1)));
 		}
 	} else {
 		unsigned off64_nr = 0;
 		struct {
-			unsigned char sha1[20];
+			struct object_id oid;
 			uint32_t crc;
 			uint32_t off;
 		} *entries;
 		ALLOC_ARRAY(entries, nr);
 		for (i = 0; i < nr; i++)
-			if (fread(entries[i].sha1, 20, 1, stdin) != 1)
+			if (fread(entries[i].oid.hash, hashsz, 1, stdin) != 1)
 				die("unable to read sha1 %u/%u", i, nr);
 		for (i = 0; i < nr; i++)
 			if (fread(&entries[i].crc, 4, 1, stdin) != 1)
@@ -77,7 +78,7 @@ int cmd_show_index(int argc, const char **argv, const char *prefix)
 			}
 			printf("%" PRIuMAX " %s (%08"PRIx32")\n",
 			       (uintmax_t) offset,
-			       sha1_to_hex(entries[i].sha1),
+			       oid_to_hex(&entries[i].oid),
 			       ntohl(entries[i].crc));
 		}
 		free(entries);
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 89d6f02969..2c2395a620 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -424,7 +424,7 @@ static int module_list(int argc, const char **argv, const char *prefix)
 		const struct cache_entry *ce = list.entries[i];
 
 		if (ce_stage(ce))
-			printf("%06o %s U\t", ce->ce_mode, sha1_to_hex(null_sha1));
+			printf("%06o %s U\t", ce->ce_mode, oid_to_hex(&null_oid));
 		else
 			printf("%06o %s %d\t", ce->ce_mode,
 			       oid_to_hex(&ce->oid), ce_stage(ce));
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 7f094f8170..fe70656327 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -350,7 +350,7 @@ static int add_worktree(const char *path, const char *refname,
 	 */
 	strbuf_reset(&sb);
 	strbuf_addf(&sb, "%s/HEAD", sb_repo.buf);
-	write_file(sb.buf, "%s", sha1_to_hex(null_sha1));
+	write_file(sb.buf, "%s", oid_to_hex(&null_oid));
 	strbuf_reset(&sb);
 	strbuf_addf(&sb, "%s/commondir", sb_repo.buf);
 	write_file(sb.buf, "../..");
diff --git a/bundle.c b/bundle.c
index b5d21cd80f..a85ed3f7bc 100644
--- a/bundle.c
+++ b/bundle.c
@@ -282,7 +282,7 @@ static int write_pack_data(int bundle_fd, struct rev_info *revs)
 		struct object *object = revs->pending.objects[i].item;
 		if (object->flags & UNINTERESTING)
 			write_or_die(pack_objects.in, "^", 1);
-		write_or_die(pack_objects.in, oid_to_hex(&object->oid), GIT_SHA1_HEXSZ);
+		write_or_die(pack_objects.in, oid_to_hex(&object->oid), the_hash_algo->hexsz);
 		write_or_die(pack_objects.in, "\n", 1);
 	}
 	close(pack_objects.in);
@@ -414,7 +414,7 @@ static int write_bundle_refs(int bundle_fd, struct rev_info *revs)
 		}
 
 		ref_count++;
-		write_or_die(bundle_fd, oid_to_hex(&e->item->oid), 40);
+		write_or_die(bundle_fd, oid_to_hex(&e->item->oid), the_hash_algo->hexsz);
 		write_or_die(bundle_fd, " ", 1);
 		write_or_die(bundle_fd, display_ref, strlen(display_ref));
 		write_or_die(bundle_fd, "\n", 1);
diff --git a/cache.h b/cache.h
index 1e64b13c90..76f38f7df0 100644
--- a/cache.h
+++ b/cache.h
@@ -1067,7 +1067,6 @@ const char *repo_find_unique_abbrev(struct repository *r, const struct object_id
 int repo_find_unique_abbrev_r(struct repository *r, char *hex, const struct object_id *oid, int len);
 #define find_unique_abbrev_r(hex, oid, len) repo_find_unique_abbrev_r(the_repository, hex, oid, len)
 
-extern const unsigned char null_sha1[GIT_MAX_RAWSZ];
 extern const struct object_id null_oid;
 
 static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)
@@ -1102,14 +1101,9 @@ static inline int oideq(const struct object_id *oid1, const struct object_id *oi
 	return hasheq(oid1->hash, oid2->hash);
 }
 
-static inline int is_null_sha1(const unsigned char *sha1)
-{
-	return hasheq(sha1, null_sha1);
-}
-
 static inline int is_null_oid(const struct object_id *oid)
 {
-	return hasheq(oid->hash, null_sha1);
+	return oideq(oid, &null_oid);
 }
 
 static inline void hashcpy(unsigned char *sha_dst, const unsigned char *sha_src)
diff --git a/combine-diff.c b/combine-diff.c
index 3e49f3bda8..d5c4d839dc 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -930,7 +930,7 @@ static void show_combined_header(struct combine_diff_path *elem,
 				 int show_file_header)
 {
 	struct diff_options *opt = &rev->diffopt;
-	int abbrev = opt->flags.full_index ? GIT_SHA1_HEXSZ : DEFAULT_ABBREV;
+	int abbrev = opt->flags.full_index ? the_hash_algo->hexsz : DEFAULT_ABBREV;
 	const char *a_prefix = opt->a_prefix ? opt->a_prefix : "a/";
 	const char *b_prefix = opt->b_prefix ? opt->b_prefix : "b/";
 	const char *c_meta = diff_get_color_opt(opt, DIFF_METAINFO);
diff --git a/config.c b/config.c
index 743e4570ee..eef4f4f1bb 100644
--- a/config.c
+++ b/config.c
@@ -1204,7 +1204,7 @@ static int git_default_core_config(const char *var, const char *value, void *cb)
 			default_abbrev = -1;
 		else {
 			int abbrev = git_config_int(var, value);
-			if (abbrev < minimum_abbrev || abbrev > 40)
+			if (abbrev < minimum_abbrev || abbrev > the_hash_algo->hexsz)
 				return error(_("abbrev length out of range: %d"), abbrev);
 			default_abbrev = abbrev;
 		}
diff --git a/connected.c b/connected.c
index 971db009b3..36c4e5dedb 100644
--- a/connected.c
+++ b/connected.c
@@ -29,6 +29,7 @@ int check_connected(oid_iterate_fn fn, void *cb_data,
 	struct packed_git *new_pack = NULL;
 	struct transport *transport;
 	size_t base_len;
+	const unsigned hexsz = the_hash_algo->hexsz;
 
 	if (!opt)
 		opt = &defaults;
@@ -100,7 +101,7 @@ int check_connected(oid_iterate_fn fn, void *cb_data,
 
 	sigchain_push(SIGPIPE, SIG_IGN);
 
-	commit[GIT_SHA1_HEXSZ] = '\n';
+	commit[hexsz] = '\n';
 	do {
 		/*
 		 * If index-pack already checked that:
@@ -113,8 +114,8 @@ int check_connected(oid_iterate_fn fn, void *cb_data,
 		if (new_pack && find_pack_entry_one(oid.hash, new_pack))
 			continue;
 
-		memcpy(commit, oid_to_hex(&oid), GIT_SHA1_HEXSZ);
-		if (write_in_full(rev_list.in, commit, GIT_SHA1_HEXSZ + 1) < 0) {
+		memcpy(commit, oid_to_hex(&oid), hexsz);
+		if (write_in_full(rev_list.in, commit, hexsz + 1) < 0) {
 			if (errno != EPIPE && errno != EINVAL)
 				error_errno(_("failed write to rev-list"));
 			err = -1;
diff --git a/diff.c b/diff.c
index 6db6927369..8fb57b73ef 100644
--- a/diff.c
+++ b/diff.c
@@ -5978,7 +5978,7 @@ static void diff_summary(struct diff_options *opt, struct diff_filepair *p)
 }
 
 struct patch_id_t {
-	git_SHA_CTX *ctx;
+	git_hash_ctx *ctx;
 	int patchlen;
 };
 
@@ -5995,16 +5995,16 @@ static int remove_space(char *line, int len)
 	return dst - line;
 }
 
-void flush_one_hunk(struct object_id *result, git_SHA_CTX *ctx)
+void flush_one_hunk(struct object_id *result, git_hash_ctx *ctx)
 {
 	unsigned char hash[GIT_MAX_RAWSZ];
 	unsigned short carry = 0;
 	int i;
 
-	git_SHA1_Final(hash, ctx);
-	git_SHA1_Init(ctx);
+	the_hash_algo->final_fn(hash, ctx);
+	the_hash_algo->init_fn(ctx);
 	/* 20-byte sum, with carry */
-	for (i = 0; i < GIT_SHA1_RAWSZ; ++i) {
+	for (i = 0; i < the_hash_algo->rawsz; ++i) {
 		carry += result->hash[i] + hash[i];
 		result->hash[i] = carry;
 		carry >>= 8;
@@ -6018,21 +6018,21 @@ static void patch_id_consume(void *priv, char *line, unsigned long len)
 
 	new_len = remove_space(line, len);
 
-	git_SHA1_Update(data->ctx, line, new_len);
+	the_hash_algo->update_fn(data->ctx, line, new_len);
 	data->patchlen += new_len;
 }
 
-static void patch_id_add_string(git_SHA_CTX *ctx, const char *str)
+static void patch_id_add_string(git_hash_ctx *ctx, const char *str)
 {
-	git_SHA1_Update(ctx, str, strlen(str));
+	the_hash_algo->update_fn(ctx, str, strlen(str));
 }
 
-static void patch_id_add_mode(git_SHA_CTX *ctx, unsigned mode)
+static void patch_id_add_mode(git_hash_ctx *ctx, unsigned mode)
 {
 	/* large enough for 2^32 in octal */
 	char buf[12];
 	int len = xsnprintf(buf, sizeof(buf), "%06o", mode);
-	git_SHA1_Update(ctx, buf, len);
+	the_hash_algo->update_fn(ctx, buf, len);
 }
 
 /* returns 0 upon success, and writes result into oid */
@@ -6040,10 +6040,10 @@ static int diff_get_patch_id(struct diff_options *options, struct object_id *oid
 {
 	struct diff_queue_struct *q = &diff_queued_diff;
 	int i;
-	git_SHA_CTX ctx;
+	git_hash_ctx ctx;
 	struct patch_id_t data;
 
-	git_SHA1_Init(&ctx);
+	the_hash_algo->init_fn(&ctx);
 	memset(&data, 0, sizeof(struct patch_id_t));
 	data.ctx = &ctx;
 	oidclr(oid);
@@ -6076,27 +6076,27 @@ static int diff_get_patch_id(struct diff_options *options, struct object_id *oid
 		len2 = remove_space(p->two->path, strlen(p->two->path));
 		patch_id_add_string(&ctx, "diff--git");
 		patch_id_add_string(&ctx, "a/");
-		git_SHA1_Update(&ctx, p->one->path, len1);
+		the_hash_algo->update_fn(&ctx, p->one->path, len1);
 		patch_id_add_string(&ctx, "b/");
-		git_SHA1_Update(&ctx, p->two->path, len2);
+		the_hash_algo->update_fn(&ctx, p->two->path, len2);
 
 		if (p->one->mode == 0) {
 			patch_id_add_string(&ctx, "newfilemode");
 			patch_id_add_mode(&ctx, p->two->mode);
 			patch_id_add_string(&ctx, "---/dev/null");
 			patch_id_add_string(&ctx, "+++b/");
-			git_SHA1_Update(&ctx, p->two->path, len2);
+			the_hash_algo->update_fn(&ctx, p->two->path, len2);
 		} else if (p->two->mode == 0) {
 			patch_id_add_string(&ctx, "deletedfilemode");
 			patch_id_add_mode(&ctx, p->one->mode);
 			patch_id_add_string(&ctx, "---a/");
-			git_SHA1_Update(&ctx, p->one->path, len1);
+			the_hash_algo->update_fn(&ctx, p->one->path, len1);
 			patch_id_add_string(&ctx, "+++/dev/null");
 		} else {
 			patch_id_add_string(&ctx, "---a/");
-			git_SHA1_Update(&ctx, p->one->path, len1);
+			the_hash_algo->update_fn(&ctx, p->one->path, len1);
 			patch_id_add_string(&ctx, "+++b/");
-			git_SHA1_Update(&ctx, p->two->path, len2);
+			the_hash_algo->update_fn(&ctx, p->two->path, len2);
 		}
 
 		if (diff_header_only)
@@ -6108,10 +6108,10 @@ static int diff_get_patch_id(struct diff_options *options, struct object_id *oid
 
 		if (diff_filespec_is_binary(options->repo, p->one) ||
 		    diff_filespec_is_binary(options->repo, p->two)) {
-			git_SHA1_Update(&ctx, oid_to_hex(&p->one->oid),
-					GIT_SHA1_HEXSZ);
-			git_SHA1_Update(&ctx, oid_to_hex(&p->two->oid),
-					GIT_SHA1_HEXSZ);
+			the_hash_algo->update_fn(&ctx, oid_to_hex(&p->one->oid),
+					the_hash_algo->hexsz);
+			the_hash_algo->update_fn(&ctx, oid_to_hex(&p->two->oid),
+					the_hash_algo->hexsz);
 			continue;
 		}
 
@@ -6128,7 +6128,7 @@ static int diff_get_patch_id(struct diff_options *options, struct object_id *oid
 	}
 
 	if (!stable)
-		git_SHA1_Final(oid->hash, &ctx);
+		the_hash_algo->final_fn(oid->hash, &ctx);
 
 	return 0;
 }
diff --git a/diff.h b/diff.h
index c2c3056810..7f8f024feb 100644
--- a/diff.h
+++ b/diff.h
@@ -438,7 +438,7 @@ int run_diff_index(struct rev_info *revs, int cached);
 
 int do_diff_cache(const struct object_id *, struct diff_options *);
 int diff_flush_patch_id(struct diff_options *, struct object_id *, int, int);
-void flush_one_hunk(struct object_id *, git_SHA_CTX *);
+void flush_one_hunk(struct object_id *result, git_hash_ctx *ctx);
 
 int diff_result_code(struct diff_options *, int);
 
diff --git a/fetch-pack.c b/fetch-pack.c
index 6ccc6294ea..947da545de 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -167,16 +167,16 @@ static enum ack_type get_ack(struct packet_reader *reader,
 	if (!strcmp(reader->line, "NAK"))
 		return NAK;
 	if (skip_prefix(reader->line, "ACK ", &arg)) {
-		if (!get_oid_hex(arg, result_oid)) {
-			arg += 40;
-			len -= arg - reader->line;
+		const char *p;
+		if (!parse_oid_hex(arg, result_oid, &p)) {
+			len -= p - reader->line;
 			if (len < 1)
 				return ACK;
-			if (strstr(arg, "continue"))
+			if (strstr(p, "continue"))
 				return ACK_continue;
-			if (strstr(arg, "common"))
+			if (strstr(p, "common"))
 				return ACK_common;
-			if (strstr(arg, "ready"))
+			if (strstr(p, "ready"))
 				return ACK_ready;
 			return ACK;
 		}
diff --git a/midx.c b/midx.c
index d649644420..f29afc0d2d 100644
--- a/midx.c
+++ b/midx.c
@@ -19,8 +19,7 @@
 #define MIDX_BYTE_NUM_PACKS 8
 #define MIDX_HASH_VERSION 1
 #define MIDX_HEADER_SIZE 12
-#define MIDX_HASH_LEN 20
-#define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + MIDX_HASH_LEN)
+#define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + the_hash_algo->rawsz)
 
 #define MIDX_MAX_CHUNKS 5
 #define MIDX_CHUNK_ALIGNMENT 4
@@ -93,7 +92,7 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local
 	hash_version = m->data[MIDX_BYTE_HASH_VERSION];
 	if (hash_version != MIDX_HASH_VERSION)
 		die(_("hash version %u does not match"), hash_version);
-	m->hash_len = MIDX_HASH_LEN;
+	m->hash_len = the_hash_algo->rawsz;
 
 	m->num_chunks = m->data[MIDX_BYTE_NUM_CHUNKS];
 
@@ -234,7 +233,7 @@ int prepare_midx_pack(struct repository *r, struct multi_pack_index *m, uint32_t
 int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result)
 {
 	return bsearch_hash(oid->hash, m->chunk_oid_fanout, m->chunk_oid_lookup,
-			    MIDX_HASH_LEN, result);
+			    the_hash_algo->rawsz, result);
 }
 
 struct object_id *nth_midxed_object_oid(struct object_id *oid,
@@ -928,7 +927,7 @@ static int write_midx_internal(const char *object_dir, struct multi_pack_index *
 
 	cur_chunk++;
 	chunk_ids[cur_chunk] = MIDX_CHUNKID_OBJECTOFFSETS;
-	chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_HASH_LEN;
+	chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * the_hash_algo->rawsz;
 
 	cur_chunk++;
 	chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_CHUNK_OFFSET_WIDTH;
@@ -976,7 +975,7 @@ static int write_midx_internal(const char *object_dir, struct multi_pack_index *
 				break;
 
 			case MIDX_CHUNKID_OIDLOOKUP:
-				written += write_midx_oid_lookup(f, MIDX_HASH_LEN, entries, nr_entries);
+				written += write_midx_oid_lookup(f, the_hash_algo->rawsz, entries, nr_entries);
 				break;
 
 			case MIDX_CHUNKID_OBJECTOFFSETS:
diff --git a/pack-write.c b/pack-write.c
index 29d17a9bec..f0017beb9d 100644
--- a/pack-write.c
+++ b/pack-write.c
@@ -349,7 +349,7 @@ void finish_tmp_packfile(struct strbuf *name_buffer,
 			 struct pack_idx_entry **written_list,
 			 uint32_t nr_written,
 			 struct pack_idx_option *pack_idx_opts,
-			 unsigned char sha1[])
+			 unsigned char hash[])
 {
 	const char *idx_tmp_name;
 	int basename_len = name_buffer->len;
@@ -358,18 +358,18 @@ void finish_tmp_packfile(struct strbuf *name_buffer,
 		die_errno("unable to make temporary pack file readable");
 
 	idx_tmp_name = write_idx_file(NULL, written_list, nr_written,
-				      pack_idx_opts, sha1);
+				      pack_idx_opts, hash);
 	if (adjust_shared_perm(idx_tmp_name))
 		die_errno("unable to make temporary index file readable");
 
-	strbuf_addf(name_buffer, "%s.pack", sha1_to_hex(sha1));
+	strbuf_addf(name_buffer, "%s.pack", hash_to_hex(hash));
 
 	if (rename(pack_tmp_name, name_buffer->buf))
 		die_errno("unable to rename temporary pack file");
 
 	strbuf_setlen(name_buffer, basename_len);
 
-	strbuf_addf(name_buffer, "%s.idx", sha1_to_hex(sha1));
+	strbuf_addf(name_buffer, "%s.idx", hash_to_hex(hash));
 	if (rename(idx_tmp_name, name_buffer->buf))
 		die_errno("unable to rename temporary index file");
 
diff --git a/packfile.c b/packfile.c
index f3f962af4c..dd4b0e51c4 100644
--- a/packfile.c
+++ b/packfile.c
@@ -20,12 +20,12 @@
 #include "promisor-remote.h"
 
 char *odb_pack_name(struct strbuf *buf,
-		    const unsigned char *sha1,
+		    const unsigned char *hash,
 		    const char *ext)
 {
 	strbuf_reset(buf);
 	strbuf_addf(buf, "%s/pack/pack-%s.%s", get_object_directory(),
-		    sha1_to_hex(sha1), ext);
+		    hash_to_hex(hash), ext);
 	return buf->buf;
 }
 
diff --git a/rerere.c b/rerere.c
index 17abb47321..3e51fdfe58 100644
--- a/rerere.c
+++ b/rerere.c
@@ -52,7 +52,7 @@ static void free_rerere_id(struct string_list_item *item)
 
 static const char *rerere_id_hex(const struct rerere_id *id)
 {
-	return sha1_to_hex(id->collection->hash);
+	return hash_to_hex(id->collection->hash);
 }
 
 static void fit_variant(struct rerere_dir *rr_dir, int variant)
@@ -115,7 +115,7 @@ static int is_rr_file(const char *name, const char *filename, int *variant)
 static void scan_rerere_dir(struct rerere_dir *rr_dir)
 {
 	struct dirent *de;
-	DIR *dir = opendir(git_path("rr-cache/%s", sha1_to_hex(rr_dir->hash)));
+	DIR *dir = opendir(git_path("rr-cache/%s", hash_to_hex(rr_dir->hash)));
 
 	if (!dir)
 		return;
@@ -186,9 +186,9 @@ static struct rerere_id *new_rerere_id_hex(char *hex)
 	return id;
 }
 
-static struct rerere_id *new_rerere_id(unsigned char *sha1)
+static struct rerere_id *new_rerere_id(unsigned char *hash)
 {
-	return new_rerere_id_hex(sha1_to_hex(sha1));
+	return new_rerere_id_hex(hash_to_hex(hash));
 }
 
 /*
diff --git a/sequencer.c b/sequencer.c
index d648aaf416..ea368bcfe9 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -3578,7 +3578,7 @@ static int do_merge(struct repository *r,
 		goto leave_merge;
 	}
 
-	write_message(oid_to_hex(&merge_commit->object.oid), GIT_SHA1_HEXSZ,
+	write_message(oid_to_hex(&merge_commit->object.oid), the_hash_algo->hexsz,
 		      git_path_merge_head(r), 0);
 	write_message("no-ff", 5, git_path_merge_mode(r), 0);
 
@@ -4497,7 +4497,7 @@ static const char *label_oid(struct object_id *oid, const char *label,
 		char *p;
 
 		strbuf_reset(&state->buf);
-		strbuf_grow(&state->buf, GIT_SHA1_HEXSZ);
+		strbuf_grow(&state->buf, GIT_MAX_HEXSZ);
 		label = p = state->buf.buf;
 
 		find_unique_abbrev_r(p, oid, default_abbrev);
@@ -4510,7 +4510,7 @@ static const char *label_oid(struct object_id *oid, const char *label,
 			size_t i = strlen(p) + 1;
 
 			oid_to_hex_r(p, oid);
-			for (; i < GIT_SHA1_HEXSZ; i++) {
+			for (; i < the_hash_algo->hexsz; i++) {
 				char save = p[i];
 				p[i] = '\0';
 				if (!hashmap_get_from_hash(&state->labels,
diff --git a/sha1-file.c b/sha1-file.c
index e85f249a5d..188de57634 100644
--- a/sha1-file.c
+++ b/sha1-file.c
@@ -55,7 +55,6 @@
 	"\x6f\xe1\x41\xf7\x74\x91\x20\xa3\x03\x72" \
 	"\x18\x13"
 
-const unsigned char null_sha1[GIT_MAX_RAWSZ];
 const struct object_id null_oid;
 static const struct object_id empty_tree_oid = {
 	EMPTY_TREE_SHA1_BIN_LITERAL
diff --git a/sha1-lookup.c b/sha1-lookup.c
index 796ab68da8..93d9af0805 100644
--- a/sha1-lookup.c
+++ b/sha1-lookup.c
@@ -50,7 +50,7 @@ static uint32_t take2(const unsigned char *sha1)
  * The sha1 of element i (between 0 and nr - 1) should be returned
  * by "fn(i, table)".
  */
-int sha1_pos(const unsigned char *sha1, void *table, size_t nr,
+int sha1_pos(const unsigned char *hash, void *table, size_t nr,
 	     sha1_access_fn fn)
 {
 	size_t hi = nr;
@@ -63,10 +63,10 @@ int sha1_pos(const unsigned char *sha1, void *table, size_t nr,
 	if (nr != 1) {
 		size_t lov, hiv, miv, ofs;
 
-		for (ofs = 0; ofs < 18; ofs += 2) {
+		for (ofs = 0; ofs < the_hash_algo->rawsz - 2; ofs += 2) {
 			lov = take2(fn(0, table) + ofs);
 			hiv = take2(fn(nr - 1, table) + ofs);
-			miv = take2(sha1 + ofs);
+			miv = take2(hash + ofs);
 			if (miv < lov)
 				return -1;
 			if (hiv < miv)
@@ -88,7 +88,7 @@ int sha1_pos(const unsigned char *sha1, void *table, size_t nr,
 
 	do {
 		int cmp;
-		cmp = hashcmp(fn(mi, table), sha1);
+		cmp = hashcmp(fn(mi, table), hash);
 		if (!cmp)
 			return mi;
 		if (cmp > 0)
diff --git a/wt-status.c b/wt-status.c
index ad6282c7f8..cc6f94504d 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -2029,7 +2029,7 @@ static void wt_porcelain_v2_print_tracking(struct wt_status *s)
 	char eol = s->null_termination ? '\0' : '\n';
 
 	fprintf(s->fp, "# branch.oid %s%c",
-			(s->is_initial ? "(initial)" : sha1_to_hex(s->sha1_commit)),
+			(s->is_initial ? "(initial)" : oid_to_hex(&s->oid_commit)),
 			eol);
 
 	if (!s->branch)
diff --git a/wt-status.h b/wt-status.h
index 77dad5b920..71c3f25f43 100644
--- a/wt-status.h
+++ b/wt-status.h
@@ -116,7 +116,7 @@ struct wt_status {
 	int rename_limit;
 	enum wt_status_format status_format;
 	struct wt_status_state state;
-	unsigned char sha1_commit[GIT_MAX_RAWSZ]; /* when not Initial */
+	struct object_id oid_commit; /* when not Initial */
 
 	/* These are computed during processing of the individual sections */
 	int committable;